Liquid tight connector with improved ground conductivity

Abstract

A liquid tight connector for joining a liquid tight flexible conduit to a junction box or panel and having improved ground continuity is provided. The connector includes a body member having a cast-on lug to which an external ground may be secured. To provide a liquid tight seal between the fitting and the junction box, channel or raceway, an O-ring or similar seal is provided. The O-ring is placed in a recess whose depth and cross section are so related to the size and characteristics of the O-ring, that when the O-ring provides a liquid tight seal, a metallic surface of the body is in contact with the joined metallic member. With this increased metallic contact, there is an improved capacity to conduct fault current. The recess may be positioned to provide substantial contact area on an appropriate side of the perimeter of the O-ring. This protects the contact area from rust and/or corrosion which would reduce the fault current carrying capacity. Serrations, or other means, may be provided to improve the contact between the connector and the joined member and to minimize any tendency to loosen due to vibration. The principles may be adapted to a wide variety of fittings.

What is claimed is: 
     
       1. An electrical fitting for attachment to an end of a flexible metal conduit, having a nonconducting liquid tight outer jacket, to provide parallel internal and external grounding connections and to facilitate coupling the conduit to a panel member and comprising in combination elements assembled in the named sequence: (a) a gland nut having internal threads and an integral ground lug;   (b) a sealing ring;   (c) a one piece ferrule having threads on an internal sleeve and including, (1) an outer sleeve having cylindrical sides and   (2) a flared lip engaging said sealing ring;     (d) a body member having, (1) an interior surface in mating engagement with the cylindrical sides of said ferrule;   (2) a first threaded end mating with the threads of said gland nut for coupling said elements together in response to the relative rotation of said body member and said gland nut, whereby there is electrical continuity between said gland nut, said body member, and said ferrule; and   (3) a second threaded end for insertion in an opening in a panel member; and     (e) a lock nut on said second threaded end for coupling said fitting to a panel member whereby said ground lug on said gland nut may be oriented at any selected angular orientation in the plane of said gland nut as said fitting is secured to the panel in response to the rotation of said lock nut on said second threaded end.   
     
     
       2. The combination as set forth in claim 1, wherein said ground lug on said gland nut has a first hole therethrough whose axis is parallel to the axis of said conduit and into which a grounding wire may be placed. 
     
     
       3. The combination as set forth in claim 2, wherein said ground lug has a threaded hole intersecting said first hole for securing a set screw which in turn secures a wire in said first hole. 
     
     
       4. The combination as set forth in claim 3, wherein said threaded hole has a diameter approximately equal to the diameter of said first hole. 
     
     
       5. An electrical fitting for an electrical and liquid tight connection to a panel member and comprising in combination: (a) a body member having a threaded member projecting therefrom with a passage through said body member and said threaded member;   (b) a ring encircling said threaded member and having: (1) a first surface for mating with said body member; and   (2) a second surface for mating with the panel member when said threaded member is inserted in an opening in the panel:     (c) an elastomeric seal comprising an endless loop encircling said threaded member; and   (d) pressure means threadingly coupled to said threaded member whereby with said threaded member inserted through the opening in the panel said pressure means can be threaded onto said threaded member for coupling said body member to the panel with a liquid tight and electrical connection in response to engagement of said pressure means with said threaded member.   
     
     
       6. The combination as set forth in claim 5, wherein said ring includes means on its outer perimeter for retaining said elastomeric seal. 
     
     
       7. The combination as set forth in claim 5, wherein said ring includes means on its inner perimeter for retaining said elastomeric seal. 
     
     
       8. The combination as set forth in claim 5, wherein at least one of said first and second surfaces has serrations for enhancing the electrical contact between said body member, said ring and the panel.